Exercise and breast cancer prevention

Breast cancer incidence trends in Golestan, Iran: An age-period-cohort analysis by ethnic region, 2004-2018

BACKGROUND

We aimed to examine the effects of age, diagnosis year (calendar period) and birth year (cohort) on the incidence trends of breast cancer among Golestan women, Northeast Iran, 2004-2018.

METHODS

Incidence data were obtained by residential status (urban/rural) and ethnic region (Turkmens/non-Turkmens). We calculated age-standardized incidence rates (ASRs) per 100,000 person-years. The estimated annual percentage change (EAPC) were calculated, and age-period-cohort (APC) models fitted to assess non-linear effects of period and cohort as incidence rate ratios (IRRs).

RESULTS

The total number of female breast cancer cases in Golestan, 2004-2018, were 3853, with an overall ASR of 31.3. We found higher rates in urban population (40.5) and non-Turkmens region (38.5) compared to rural area (20.8) and Turkmens region (20.2), respectively. There were increasing trends in incidence rates overall (EAPC= 4.4; 95%CI: 2.2, 6.7), with greater changes in rural areas (EAPC=5.1), particularly among non-Turkmens (EAPC=5.8). The results of the APC analysis indicate the presence of significant non-linear cohort effects with increasing IRRs across successive birth cohorts (IRR=0.1 and IRR= 2.6 for the oldest and the youngest birth cohorts vs. the reference birth cohort, respectively).

CONCLUSION

We found increasing trends in breast cancer incidence among Golestan women over the study period, with disparities in patterns and trends by residence area and ethnic region. The observed cohort effects suggest an increasing prevalence of key risk factors for breast cancer in this Iranian population. Further investigations are warranted to clarify the relationships between determinants such as reproductive factors and ethnicity in the region.

Global Increase in Breast Cancer Incidence: Risk Factors and Preventive Measures

Breast cancer is a global cause for concern owing to its high incidence around the world. The alarming increase in breast cancer cases emphasizes the management of disease at multiple levels. The management should start from the beginning that includes stringent cancer screening or cancer registry to effective diagnostic and treatment strategies. Breast cancer is highly heterogeneous at morphology as well as molecular levels and needs different therapeutic regimens based on the molecular subtype. Breast cancer patients with respective subtype have different clinical outcome prognoses. Breast cancer heterogeneity emphasizes the advanced molecular testing that will help on-time diagnosis and improved survival. Emerging fields such as liquid biopsy and artificial intelligence would help to under the complexity of breast cancer disease and decide the therapeutic regimen that helps in breast cancer management. In this review, we have discussed various risk factors and advanced technology available for breast cancer diagnosis to combat the worst breast cancer status and areas that need to be focused for the better management of breast cancer.

Adult Physical Activity and Breast Cancer Risk in Women with a Family History of Breast Cancer

BACKGROUND

Recreational physical activity has been consistently associated with reduced breast cancer risk. Less is known about how family history of breast cancer affects the association and whether it varies by menopausal status.

METHODS

The Sister Study is a cohort of 50,884 women who had a sister with breast cancer but no prior breast cancer themselves at enrollment. Women reported all recreational sport/exercise activities they participated in over the past 12 months. Hours/week and MET-hours/week of physical activity were considered in association with breast cancer risk. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated with Cox regression. Extent of family history, examined as a modifier, was characterized by a Bayesian score incorporating characteristics of the family structure.

RESULTS

During follow-up (average 8.4 years), 3,023 cases were diagnosed. Higher hours/week (HR_≥7vs<1 = 0.77; 95% CI, 0.66-0.90) and MET-hours/week (HR_quartile4vs1 = 0.75; 95% CI, 0.67-0.85) of physical activity were associated with reduced postmenopausal breast cancer risk. Hours/week and MET-hours/week were associated with suggestively increased premenopausal breast cancer risk (MET-hours/week HR_quartile4vs1 = 1.25; 95% CI, 0.98-1.60). Associations did not vary with extent of family history. However, the increased risk in premenopausal women may be limited to those with stronger family history.

CONCLUSIONS

In women with a family history of breast cancer, physical activity was associated with reduced postmenopausal, but not premenopausal, breast cancer risk and was not modified by extent of family history.

IMPACT

This was the first study to examine the association between physical activity and breast cancer risk in a large population with a family history of breast cancer.

Pregnancy-associated breast cancer: the risky status quo and new concepts of predictive medicine

The paper is motivated by severe concerns regarding currently applied care of the pregnancy-associated breast cancer (PABC) characterised by particularly poor outcomes of the disease. Psychological and ethical aspects play a crucial role in PABC: the highest priority not to damage the foetus significantly complicates any treatment generally, and it is quite usual that patients disclaim undergoing any breast cancer treatment during pregnancy. Although, due to global demographic trends, PABC is far from appearing rarely now, severe societal and economic consequences of the disease are still neglected by currently applied reactive medical approach. These actualities require creating new strategies which should be better adapted to the needs of the society at large by advancing the PABC care based on predictive diagnostic approaches specifically in premenopausal women, innovative screening programmes focused on young female populations, targeted prevention in high-risk groups, and optimised treatment concepts. The article summarises the facts and provides recommendations to advance the field-related research and medical services specifically dedicated to the PABC care.

Leisure time physical activity and cancer risk: evaluation of the WHO's recommendation based on 126 high-quality epidemiological studies

BACKGROUND

The WHO has concluded that physical activity reduces the risk of numerous diseases. However, few systemic reviews have been performed to assess the role of leisure time physical activity (LTPA) in lowering the risk of cancer in a dose-dependent manner and furthermore the suitability of recommendation of physical activity by the WHO.

METHODS

A systematic review and meta-analysis was designed to estimate cancer risk by LTPA in binary comparison and in a dose-dependent manner. MEDLINE and Web of Science were searched up to 30 December 2014 without language restrictions. Reference lists were reviewed for potential articles.

RESULTS

A total of 126 studies were recruited into the meta-analysis. Overall, the total cancer risk was reduced by 10% in people who undertook the most LTPA as compared with those who did the least. Dose-response meta-analysis indicated that the current WHO recommendation (equal to an average of 10 metabolic equivalents of energy hours per week) induced a 7% (95% CI 5% to 9%) cancer reduction. Moreover, the protective role of LTPA against cancer becomes saturated at 20 metabolic equivalents of energy hours per week, with a relative risk of 0.91 (95% CI 0.88 to 0.93). Subanalyses results based on cancer types showed that LTPA only exhibited significant protection against breast cancer and colorectal cancer.

CONCLUSIONS

Our meta-analysis indicates that the current WHO recommendation of physical activity can result in a 7% reduction in cancer risk, which is mainly attributed to its protective role against breast cancer and colorectal cancer. Furthermore, two-fold of current recommendation level is considered to give its saturated protection against cancer.

Lifestyle and Breast Cancer Incidence and Survival

Recently reported SEER data revealing an increase in the number of younger women who present with advanced breast cancer at diagnosis has led to much speculation regarding epidemiological factors that play a role in breast cancer risk and that may be modifiable by lifestyle. Molecular genomics has identified biological pathways that affect breast cancer prognosis and inform treatment decisions. Depending on menopausal status and breast cancer subtype, evidence is emerging that lifestyle could be implicated not only in the risk for breast cancer but also outcomes following breast cancer diagnosis. Several biologic mechanisms have been explored explaining the physiologic role of lifestyle and cancer risk and survival. In this report, we explore the interaction between lifestyle, breast cancer phenotype, and outcomes and review potential molecular mechanisms linking lifestyle to risk and prognosis in order to establish a platform for future exploration. The cost of breast cancer treatment and breast cancer morbidity and mortality during a woman’s productive years impose a psychosocial and socioeconomic burden on our nation. Efforts to ease that burden through lifestyle modification should be embraced and supported as we reevaluate and scrutinize the allocation of health care resources in our nation.

The role of physical exercise in the development of breast cancer

Breast cancer is one of the most common types of cancer among women worldwide. Epidemiological and experimental studies confirm the beneficial effects of physical exercise both in patients who have suffered a relapse and in those who are in the course of a treatment. Researchers suggest that regular physical effort performed 3-5 times a week at 20-40 MET reduces the risk of development of breast cancer. Scientific evidence suggests that aerobic training can be safe and effective even during the oncological treatment, which, depending on the stage of the disease, may consist of surgical treatment combined with chemotherapy, radiotherapy or hormone therapy. In addition, it significantly improves the function of the circulatory and respiratory systems, reduces fatigue and improves the quality of life of patients struggling with the disease. There are many theories on the mechanisms that are triggered by aerobic workout. Despite the numerous studies on this subject, which have been conducted over the years, we still cannot say how physical activity reduces the risk of development of breast cancer. The most frequently mentioned biological mechanisms include the influence of oestrogen, metabolic hormones, growth factor, inflammatory markers, response from the immune system, insulin resistance and oxidative stress. Many studies into the process of carcinogenesis are carried out in laboratory conditions on animals. Due to application of different experimental models, the results of such studies are often ambiguous. Nevertheless, scientists see a huge potential in this kind of experiments, because some of them have already attested to the protective effects of physical exercise against the appearance of breast cancer, but also they have increased our understanding of the processes through which this risk is reduced. Perhaps, in the future physical activity will become a part of a cancer treatment thanks to the results of such studies.

Risk determination and prevention of breast cancer

Breast cancer is an increasing public health problem. Substantial advances have been made in the treatment of breast cancer, but the introduction of methods to predict women at elevated risk and prevent the disease has been less successful. Here, we summarize recent data on newer approaches to risk prediction, available approaches to prevention, how new approaches may be made, and the difficult problem of using what we already know to prevent breast cancer in populations. During 2012, the Breast Cancer Campaign facilitated a series of workshops, each covering a specialty area of breast cancer to identify gaps in our knowledge. The risk-and-prevention panel involved in this exercise was asked to expand and update its report and review recent relevant peer-reviewed literature. The enlarged position paper presented here highlights the key gaps in risk-and-prevention research that were identified, together with recommendations for action. The panel estimated from the relevant literature that potentially 50% of breast cancer could be prevented in the subgroup of women at high and moderate risk of breast cancer by using current chemoprevention (tamoxifen, raloxifene, exemestane, and anastrozole) and that, in all women, lifestyle measures, including weight control, exercise, and moderating alcohol intake, could reduce breast cancer risk by about 30%. Risk may be estimated by standard models potentially with the addition of, for example, mammographic density and appropriate single-nucleotide polymorphisms. This review expands on four areas: (a) the prediction of breast cancer risk, (b) the evidence for the effectiveness of preventive therapy and lifestyle approaches to prevention, (c) how understanding the biology of the breast may lead to new targets for prevention, and (d) a summary of published guidelines for preventive approaches and measures required for their implementation. We hope that efforts to fill these and other gaps will lead to considerable advances in our efforts to predict risk and prevent breast cancer over the next 10 years.

[Is physical activity an elixir?]

Physical exercise has systemic effects, and it can regulate all the organs. The relative maximal aerobic oxygen uptake (VO2max) could have been important in the evolution of humans, since higher VO2max meant better hunting abilities for the Stone Age man. However, it appears that high level of VO2max is also important today, in the 21st century to prevent cardiovascular diseases, cancer and neurodegenerative diseases. High level of VO2max is not just preventive against a wide spectrum of diseases, but it associated with better function of many organs. Relevant data suggest that high level of VO2max is a key factor in prevention of diseases and survival even at the modern civilized world.

Physical activity and sex hormone levels in estradiol- and placebo-treated postmenopausal women

OBJECTIVE

Postmenopausal changes in the hormonal milieu in women with or without hormone therapy are hypothesized to be the pathway for a number of menopause-associated modifications in physiology and disease risk. Physical activity may modify these changes in women's hormone profiles. The crucial yet complex relationship between physical activity and physiologic and pharmacologic sex hormone levels in postmenopausal women has not been investigated sufficiently.

METHODS

Using structured recall, physical activity was assessed longitudinally during a period of 2 years in 194 postmenopausal women (90 randomized to 1 mg 17β-estradiol treatment daily and 104 randomized to placebo) in the Estrogen in the Prevention of Atherosclerosis Trial. The levels of physical activity were correlated with the serum sex hormone and the serum hormone-binding globulin levels in each treatment group.

RESULTS

Among the placebo-treated women, total energy expenditure was positively associated with sex hormone-binding globulin (SHBG; P < 0.001) and inversely associated with testosterones (total, bioavailable, or free) and androstenedione (P < 0.001 for all), as well as with estradiol (P = 0.02). In estradiol-treated women, estradiol levels were inversely associated with total energy expenditure (P = 0.002) and weekly hours spent in moderate or more vigorous physical activity (P = 0.001).

CONCLUSIONS

Physical activity is associated with lower serum levels of estradiol in both hormone therapy-treated and untreated women. In placebo-treated women only, physical activity is associated with reduced androgen levels and elevated SHBG levels.

Physical activity and breast cancer prevention

Breast cancer is the most commonly diagnosed invasive malignancy and the second leading cause of cancer death in women. This chapter considers epidemiologic evidence regarding the association between physical activity and breast cancer risk from 73 studies conducted around the world. Across these studies there was a 25% average risk reduction amongst physically active women as compared to the least active women. The associations were strongest for recreational activity, for activity sustained over the lifetime or done after menopause, and for activity that is of moderate to vigorous intensity and performed regularly. There is also some evidence for a stronger effect of physical activity amongst postmenopausal women, women who are normal weight, have no family history of breast cancer, and are parous. It is likely that physical activity is associated with decreased breast cancer risk via multiple interrelated biologic pathways that may involve adiposity, sex hormones, insulin resistance, adipokines, and chronic inflammation. Future research should include prospective observational epidemiologic studies relating proposed biomarkers to breast cancer risk and also randomized controlled trials to examine how physical activity influences the proposed biomarkers. Exercise trials will provide more clarity regarding the appropriate type, dose, and timing of activity that relate to breast cancer risk reduction.

Physical activity and breast cancer: review of the epidemiologic evidence and biologic mechanisms

Breast cancer is the most commonly diagnosed invasive malignancy and the second leading cause of cancer death in women globally. This review considers epidemiologic evidence regarding the association between physical activity and breast cancer risk. Across these studies there was a 25% average risk reduction among physically active women as compared to the least active women. The associations were strongest for recreational activity, for activity sustained over the lifetime or done after menopause, and for activity that is of moderate to vigorous intensity and performed regularly. There is also some evidence for a stronger effect of physical activity among postmenopausal women, women who are normal weight, have no family history of breast cancer, and are parous. It is likely that physical activity is associated with decreased breast cancer risk via multiple interrelated biologic pathways that may involve adiposity, sex hormones, insulin resistance, adipokines, and chronic inflammation. Future research should include prospective observational epidemiologic studies relating proposed biomarkers to breast cancer risk and also randomized controlled trials to examine how physical activity influences the proposed biomarkers. Exercise trials will provide more clarity regarding the appropriate type, dose, and timing of activity that are related to breast cancer risk reduction.Breast cancer remains a leading cause of cancer incidence and mortality in most developed countries worldwide. While significant international research has examined risk factors for breast cancer, most identified risk factors are nonmodifiable. During the past 20 years, over 90 studies have been conducted worldwide that have examined some aspects of the association between physical activity and breast cancer risk reduction. The purpose of this chapter is to review both the epidemiologic evidence and hypothesized biologic mechanisms whereby physical activity may influence breast cancer risk.